(define sum 0)
(define (3or5 start limit inc)
   (if (< start limit)
      (begin
         (if (= (remainder start 3) 0) (set! sum (+ sum start)) (if (= (remainder start 5) 0) (set! sum (+ sum start))))
         (3or5 (+ start inc) limit inc))) sum)

(print (3or5 0 1000 1))